Re: [RFC] allow multi-core guests: introduce cores= option to -cpu

From: Avi Kivity <avi@redhat.com>
To: Andre Przywara <andre.przywara@amd.com>
Cc: anthony@codemonkey.ws, qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: Re: [RFC] allow multi-core guests: introduce cores= option to -cpu
Date: Sat, 04 Jul 2009 18:25:16 +0300	[thread overview]
Message-ID: <4A4F745C.8010001@redhat.com> (raw)
In-Reply-To: <1246632116-31366-1-git-send-email-andre.przywara@amd.com>

On 07/03/2009 05:41 PM, Andre Przywara wrote:
> Hi,
>
> currently SMP guests happen to see<n>  vCPUs as<n>  different sockets.
> Some guests (Windows comes to mind) have license restrictions and refuse
> to run on multi-socket machines.
> So lets introduce a "cores=" parameter to the -cpu option to let the user
> specify the number of _cores_ the guest should see.
>
> This patch has not been tested with all corner cases, so I just want to
> hear your comments whether
> a) we need such an option  and
> b) you like this particular approach.
>
> Applying this qemu.git patch to qemu-kvm.git fixes Windows SMP boot on
> some versions, I successfully tried up to -smp 16 -cpu host,cores=8 with
> WindowsXP Pro.
>
>    

I thought of using -smp [processors=]2,cores=4,threads=2 (for a total of 
16 threads), but I think it makes more sense with -cpu.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.